A blood analyzer aspirates blood in a blood collection tube, mixes the aspirated blood sample with a reagent such as hemolyzing agent to prepare a measurement sample. The blood analyzer then measures the measurement sample, analyzes measurement data obtained by the measurement, and acquires an analysis result, such as the number of blood cells.
For instance, when detecting the number of white blood cells through a method referred to as flow cytometry, a blood sample is sent to an optical detector (flow cell) after red blood cells in the blood sample are hemolyzed by a hemolyzing agent and the blood sample is diluted.
In the optical detector, laser light is irradiated on the blood cells. The blood analyzer prepares a two dimensional distribution chart (scattergram) of the particles based on the forward scattered light and the lateral scattered light obtained by the irradiation with the laser light.
U.S. Pat. No. 6,979,570 discloses a particle analyzer as described above. In the particle analyzer disclosed in U.S. Pat. No. 6,979,570, the white blood cells are classified based on the scattergram, and the number of white blood cells is calculated.
The inventors found the following problems in detecting the number of particles in the analyzer. When lipid particles in the blood increase through administration of lipid emulsion to the patient, as shown in FIG. 12, the lipid particles appear on the scattergram. Therefore, when the number of white bloods cells is detected based on the scattergram, a greater number of white blood cells than the actual number of white blood cells is detected due to the presence of lipid particles, and the number of reported white blood cells is a pseudo-high value. FIG. 12 is obtained by the measurement performed by the analyzer of the present embodiment.
If the membrane resistance of red blood cells is high, hemolysis is sometimes poor where the red blood cells are not sufficiently hemolyzed by the hemolyzing agent. The particles of poor hemolysis also appear on the scattergram as measurement data, as shown in FIGS. 13 and 14. Therefore, if the number of white blood cells is detected based on such a scattergram, a greater number of white blood cells than the actual number of white blood cells is detected due to the presence of particles of poor hemolysis, and the number of reported white blood cells is a pseudo-high value. FIGS. 13 and 14 are also obtained by the measurement performed by the analyzer of the present embodiment.